Anyone seen these before? Listed as a product in the Wing World magazine, available from Wingstuff.
http://www.centramatic.com/wheel-balancer.rhtml?modelNumber=MGW100-103Seems you mount behind your rotor disc, and never remove them again.
Looks like they are a ring, which I figure is filled with the standard balancing bead.
Price kind of high for me, would rather just put the standard balancing beads in the tire. Inexpensive if you bought the 5lb jar, like I did.